Participation based
Nebula computes the space and the bandwith you're contributing to the system, and rewards you accordingly.
We are trying to create a new genre of cloud
where you don't need datacenters
to access your pictures
Security
Your data is cyphered with top-notch algorithms (AES 256). Offering your hard drive space does not make you liable for what other users put on it.
Just like any other cloud
It does work like any other cloud.
That's it.